FIGURE 5.
Influence of Na+ on the chromogenic activity of FXa. The initial velocity of peptidyl substrate hydrolysis (SpecXa, 100 μm) catalyzed by free FXa as a function of the NaCl concentration (0–450 mm) as described under “Experimental Procedures.” A, PDFXa (▪), rFXa (○), 2 nm final. B, rFXaI16L (▴), rFXaV17A (⋄), 50 nm final. The solid lines were drawn following analysis of all data sets to a rectangular hyperbola; the fitted parameters are given in the text. The data are representative of two to three similar experiments.